I. Field of the Invention
This invention relates generally to an apparatus used for the therapeutic manipulation of a person's feet, and more particularly to an apparatus for stimulating blood flow in the legs and ankles to reduce the development of deep vein thromboses (DVT), leg edema, muscular atrophy and ankle joint stiffness in postoperative orthopedic patients.
II. Discussion of the Prior Art
Deep vein thromboses (DVT) occurs in approximately 50% of patients who undergo major orthopedic surgery. Pulmonary embolism (PE) is a potentially life-threatening complication of DVT. Studies show that general anesthetics, lengthy surgical operations, and vessel damage predispose the surgical candidate to venous thrombosis formation. To reduce incidents of deep vein thrombosis and subsequent pulmonary embolus, operative nurses should be proficient in detecting patients at risk for DVT through their perioperative nursing assessments. Options available for preventing DVT are individualized according to each patient's disease, degree of risk, and a period the patient is at risk.
Several methods of treatment are effective when a timely diagnosis is made. One treatment is immediate intravenous heparin therapy, which is continued for seven to ten days. Heparin does not dissolve the thrombus, but it does prevent the clot from enlarging. Warfarin sodium (Coumadin), an oral anti-coagulant, may be used instead of, or in conjunction with, heparin for perioperative anticoagulation therapy for orthopedic surgical patients. Warfarin may be given after the acute episode. It is used for up to six months to provide additional prophylaxis until risk factors have decreased. These patients are at greater potential risk for further episodes of PE.
Thrombolytic therapy successfully dissolves clots and is frequently used in treating hemodynamically comprised patients or those with significant cardiopulmonary disease. This modality includes the drugs streptokinase, urokinase, and tissue plasminogen activator.
The perioperative use of pneumatic compressive stockings and anti-coagulants is another available treatment for significantly reducing the incidents of DVT. These measures are initiated prior to anesthesia and before injury to any blood vessel occurs. Pneumatic stockings may also be initiated several hours or days before surgery. However, pneumatic stockings have been found to be uncomfortable, tending to decrease patient compliance. The drawbacks of using warfarin include bleeding complications, and the great expense for treatment compared to pneumatic compression. Pneumatic compression stockings are used until the patient is ambulating and using muscle action in the lower extremities to produce sufficient venous return.
It has been found that exercise increases blood flow to the distal extremities, and including those in which normal blood flow has been obstructed. Foot exercising devices having a pair of foot pads which undergo reciprocating motion are known to be useful in preventive treatment of thromboembolism of bed ridden patients. Such devices are known to be either motor driven or manually operated by the patient to derive the benefits of exercise. These prior art exercising devices suffer from being overly complicated in design, and/or they tend to unwantedly move the patient's leg and knee which can cause pain or degrade the effectiveness of the therapy of the patient's ankle.
One such foot exercising device is disclosed in U.S. Pat. No. 3,318,304. This device suffers in that the heel of the patient's foot is arcuately rotated about a fixed pivot point which causes the patient's knee to bend. Thus, this device cannot exercise the patient's ankle only without affecting flexure of the patient's knee. Other devices for stimulating the circulation of blood in the feet and legs are disclosed in U.S. Pat. Nos. 3,789,836 and 3,917,261.